Next generation Web 2.0 communities and distributed P2P systems rely on
the cooperation of diverse user populations spread across numerous
administrative and security domains. Zero accountability via anonymous
online identities and divergent interests result in selfish behavior
that can disrupt or manipulate networks for personal gain. While
“reputation systems” are recognized as a promising means to
establish social control for such communities, developing reliable
reputation systems remains a challenge. Several unaddressed threats
still limit the effectiveness of reputation systems. Furthermore, most
existing work on reputations has focused on accurate reputations for
stable systems, but not examined the implications of integrating user
reputations into scalable distributed infrastructures. The primary goal
of this paper is to investigate and address the critical open challenges
that limit the effectiveness of reputations. First, we identify a
thorough taxonomy on reputation management, and use it as our framework
to classify adversarial threats that compromise reliable operation of
reputation systems. Second, we survey existing research to address these
threats. Finally, we present our solutions to address the two leading
reasons for erroneous and misleading values produced by reputation
systems today, i.e., user collusion and short-lived online identities.
We believe that this paper not only serves as an introduction to
reputation systems design, but will also help researchers deploy
reliable reputation solutions that contribute towards improving the
performance of large distributed applications.